Method of restorative dentistry



April 9, 1968 F. H. NEALON 3,376,643

METHOD OF RESTORATIVE DENTISTRY Filed Jan.- 5, 1965 INVENTOR. FRANK H.NEALON a/zsw ATTORNEY United States Patent 3,376,643 METHOD OFRESTORATIVE DENTISTRY Frank H. Nealon, Cleveland, Ohio, assignor to TheJ. M. Ney Qompany, Bloomfield, Conn., a corporation of Connecticut FiledJan. 5, 1965, Ser. No. 423,484 4 Claims. (Cl. 3267) ABSTRACT OF THEDISCLOSURE There is disclosed a method of restorative dentistry whereinthe patients tooth is initially marked with the desired location forparallel pin holes to receive the pins on a restorative device. Anegative impression is made of the patients teeth including the markingfor the desired location and a model of the teeth is formed from thenegative impression which includes the markings for the parallel pinholes. A tubular bushing is positioned over the marked locations for theparallel pin holes and the bushings are aflixed in a common base forminga removable negative impression of the model and thereby the teeth.Parallel pin holes are drilled in the model through the bushings and afitted restorative device is formed from the model including parallelpins which are spaced and aligned in accordance with the pin holesdrilled in the model. The negative impression is then fitted over thepatients teeth and holes are drilled in the patients teeth through thebushing by use of a drill driven by a flexible coupling. Finally therestorative device is affixed to the patients teeth by inserting theparallel pins into the parallel holes.

This invention relates to restorative dentistry and more particularly toa method and apparatus adapted to facilitate fabrication of restorativedevices such as dental castlugs and periodontal splints having parallelpins and to the precision drilling of parallel pinholes in a patientsteeth to receive such parallel pins for the secure and positiveretention of such restorative devices.

The use of multiple, spaced parallel holes in a patients teeth for theretention of cast dental restorations having aligned parallel pins whichare received in the parallel holes has been known in the prior art andemployed where it is desirable to avail of its advantages. This generaltechnic has the desirable features of otfering positive retention of therestorative device, conservation of tooth structure of the teethinvolved and improved aesthetics. Of the several methods and procedureswhich have been devised to carry out this technic, a number involve theuse of instrumentation and devices which are secured in a patients mouthto assure parallel alignment of a conventional hand drill to prepare thepatients teeth and drill spaced parallel holes for the reception of arestorative device having identically spaced and aligned parallel pins.In prior art methods a negative impression was then taken of thepatients teeth including the parallel holes therein and an appropriaterestorative dental device prepared and fabricated from such negativeimpression, usually at a dental laboratory equipped to fabricate suchrestorative dental devices which may take the form of gold castings, forexample.

One type of prior art device which was secured in a patients mouth toassure the parallel alignment of holes drilled with a conventionaldental drill handpiece, provided a movable guide means adapted toreceive the dental drill and permit only one angular disposition of thedrill and the handpiece driven by it. Moreover, in prior art technicsand procedures, the parallel holes were first drilled in the patientsteeth, a negative impression taken of the prepared teeth, and then therestorative 3,376,643 Patented Apr. 9, 1968 device was fabricated at adental laboratory from such negative impression. Accordingly, theprocess of fabrication of the restorative device may take several daysor frequently more and during such time there is an everpresent dangerthat the prepared parallel holes in the patients teeth may be exposed toforeign material, bacteria, infection or other undesirablecomplications. As is evident to those skilled in the art, prior artapparatus presently known to the profession often has relativelycumbersome and awkward aspects in use, in addition to requiringconsiderable experience with a particular type of instrumentation fordrilling parallel cavities to develop the highest skillfulness in itsuse and thereby assure the desirable advantages of the parallel pin typeof restorative dentistry.

A principal object of the invention is to device a method and means forfabricating a restorative dental device having pins disposed in exactparallelism for retention on a patients teeth and for thereafterdrilling parallel holes in at least one of a patients teeth with a highdegree of accuracy for receiving the parallel pins of such restorativedevice.

Another object of the present invention is to provide a method andapparatus for restorative dentistry in the application of the parallelpin technic through the use of an improved and novel drill means.

Still another object of the present invention is to provide a method andprocedure for the application of the parallel pin technic of restorativedentistry which permits the preparation and fabrication of therestorative device, including its parallel aligned pins before theparallel holes are drilled in the patients teeth, thereby allowing theinsertion of the restorative device immediately after drilling theparallel holes and eliminating certain undesirable dangers which wereinherent in prior art technics.

These and other objects and features of the invention will be more fullyunderstood from the following detailed description and accompanyingdrawings and its scope will be pointed out in the appended claims.

In the drawings:

FIGURE 1 is a perspective view of tubular bushings being aligned inparallel relationship over preestablished locations on a positive modelof a patients teeth;

FIGURE 2 is a perspective view of a matrix having a plurality ofparallel aligned bushings aflixed thereto and forming a common removablenegative impression of the model of the patients teeth shown in FIGURE 1including several approximate teeth;

FIGURE 3 is a perspective view illustrating the step of drillingparallel holes in a model of a patients teeth employing the flexiblecoupling of the present invention and the matrix base supporting theparallel tubular bushings as shown in FIGURE 2;

FIGURE 4 is a view of the matrix including the parallel tubular bushingsas shown in FIGURES 2 and 3 fitted to a patients teeth for drilling ofparallel pin holes with the flexible coupling illustrated in detail inFIGURES 5 and 5a;

FIGURE 5 is a perspective view of the flexible coupling assembly of thepresent invention; and

FIGURE 5a is an exploded perspective View of the elements comprising theflexible coupling assembly of the present invention.

The method and procedure of restorative dentistry of y the presentinvention includes the steps of preparing a patients teeth byestablishing the desired location for parallel holes on at least one ofthe patients teeth for receiving and retaining the parallel pins of arestorative device. A negative impression is then made of the patientsteeth and a positive model is formed from such negative impression. Atubular bushing is then positioned and affixed over each of thepreestablished desired locations of parallel holes, the bushings beingarranged and afiixed to a common base which forms a matrix type ofremovable negative impression of the model. While the matrix basesupporting the parallel tubular bushings is positioned on the model,parallel holes are drilled through the bushings by the use of a drilldriven through a flexible coupling. Such flexible coupling, inaccordance with the concept of the present invention, permits deviationof the alignment of the driving member (which usually comprises thehandpiece of dental drilling equipment) with respect to the drill. Thealignment deviation may be as much as twenty degrees, yet the drill willprecisely follow the pre-fixed alignment of the tubular bushing. Thusthe criticality of the drilling technic is diminished and parallel holesare assured by reason of the virtual elimination of the possibility ofthe drill binding in the guiding means, i.e., the parallel alignedbushings.

In accordance with the concept of the present invention tubular bushingsof varying lengths may be chosen so as to predetermine the maximum depthof each parallel hole to be drilled when used with a drill of knownlength. After the parallel holes have been drilled in the model of thepatients teeth, the common base in the form of a removable negativematrix-like impression supporting the parallel bushings is removed fromthe model and a fitted restorative device, usually in the form of castgold, is formed from the model including parallel pins spaced andaligned in accordance with the parallel holes previously drilled in themodel. The restorative device thus fabricated and the removable negativeimpression including the parallel tubular bushings are then sent to thedentist, who in turn fits the removable negative matrix impressionincluding the bushings, over the patients teeth preferably includingseveral approximate teeth to assure perfect alignment of the paralleltubular bushings over. the desired location of holes. The dentist thendrills parallel holes in the patients teeth at the desired locations bydrilling through the bushing guides using a drill driven by a flexiblecoupling in the manner previously described in connection with theparallel holes drilled in the model of the patients teeth. When suchdrilling procedure has been completed, the patient may immediately befitted with the restorative device by insertion of the parallel pins ofthe device into the aligned parallel holes in the appropriate desiredlocations drilled as described above. Thus, the concept of the presentinvention eliminates the problem of drilled cavities being exposed toforeign material, bacteria, and other undesirable conditions over aperiod of time which was usually the case with prior art procedures.Moreover, in accordance with the method and procedure of the presentinvention, the patient undergoes considerably less discomfort in thatthe drilling and fitting necessary in accordance with the restorativeprocedure may be accomplished at one time. Additionally, as will beevident to those skilled in the art, the parallelism of the tubularbushings which guide the drill may be established in a dental laboratoryunder convenient and highly controlled conditions rather than beingeffected in the interior of the patients mouth at a sitting in thedentists ofiice, thus assuring a higher degree of parallel alignment ofboth the tubular bushings and the restorative device which is made fromthe model of the patients teeth including parallel holes drilled by theuse of the prealigned parallel tubular bushings.

The initial step of the method and procedure of the present inventionconsists of the dentist establishing the desired location for parallelholes on at least one of the teeth which are being prepared to receive arestorative dental device. This may be done by making a smallindentation on such tooth or teeth using a burr on the enamel, forinstance. The dentist then takes an impression of the patients teethwhich is sent to a dental laboratory. There a model of the patientsteeth including the preestablished desired location for parallel holesis formed from the negative impression. Such a model is shown in partialview in FIGURE 1, generally indicated at 16.-

Suitable instrumentation such as the Ney Surveyor is then employed toalign tubular bushings as shown at 11 1 in parallel relationship at thedesired angle and over the preestablished desired locations as indicatedat 11a,- 12a and 13a. This is accomplished by placing the model in thesurvey table and aligning pin 14 in the spindle 15";

of the surveyor 16. The surveyor table (not shown) is tilted so that thealigning pin 14 is angularly disposed with respect to the model at thedesired angle that the parallel holes will take. A drill bushing such asthat,

desired by aligning the aligning pin 14 of the surveyor 16 over theadditional preestablished desired locations for parallel holes. Suchadditional bushings are shown in phantom outline at 12 and 13.

As shown in FIGURE 2 an appropriate base is formed over severalapproximate teeth including the parallel aligned bushings 11, 12 and 13by applying a suitable may terial such as a quick curing acrylic, ,forexample. Such a base is in effect a matrix and includes an index formedfrom the occlusal surfaces of several of the approximating teeth such as18 and 19 as shown in FIGURE 2.

Parallel holes are then drilled in the model 10 as shown 1 in FIGURE 3by inserting a drill 20 into each of the parallel aligned tubularbushings 11, 12 and 13 and driving the drill 20 through a flexiblecoupling 21. fitted to a conventional handpiece 22. The flexiblecoupling 21 is so conceived in accordance with the present inventionthat it allows limited angular deviation of the driving means such asthe handpiece 22 with respect to the driven drill 20 without impairingthe parallelism of the drilled holes which are guidingly drilled in themodel 10 through the parallel aligned bushings 12 and 13. The use ofsuch a flexible coupling obviates much of the criticality of drilling inparallelism since the drill 20 is free to follow the predeterminedalignment of the parallel tubular bushings 11, 12 and 13 without bindingor undue friction, regardless of the fact that the handpiece 22 maydeviate angularly as much as twenty degrees with respect to thealignment of the driven drill 20.

After the parallel holes have been drilled in the model 10 in the mannerdescribed, the base 17 is removed from the model and a restorativedevice fabricated including parallel pins spaced and aligned inparallelism in accordance with the parallel pin holes drilled in themodel. Such a restorative device may typically comprise fixed bridgeworkor periodontal splints formed of cast gold. The restorative devicetogether with the matrix base 17 including the parallel positionedhollow tubular bushings 11, 12 and 13 are then forwarded to the dentist.The in dex formed by the inclusion of the occlusal surfaces of severalof the approximating teeth on the matrix base 17 provide a means ofprecisely positioning the base 17 in the patients mouth upon his teethso that the parallel bushings 11,12 and 13 are exactly aligned over thedesired location of the parallel pin holes.

As shown in FIGURE 4, holes are then drilled by the use of a drilldriven by a flexible coupling 21 of the type previously described inconnection with FIGURE 3 by means of a conventional dental drillingapparatus such as the handpiece 22. Upon completion of the drilling andpreparation procedure, the restorative device is aflixed to the patientsteeth by insertion of the parallel pins into the drilled parallel holeswhich are aligned and spaced in accordance with the dispositionof thepins of the restorative device. Thus, it'may be seen that in accordancewith the concept of the present invention, the drilling of the parallelholes for retention of the restorative device may be accomplishedimmediately preceding the fitting of the restorative device to thepatients teeth. This procedure has the advantage of eliminating anyunwanted exposure of drilled cavities to foreign material, bacterialaction or other dangers.

A preferred embodiment of the flexible coupling conceived by the presentinvention is shown in FIGURE 5 in an assembled perspective view. Asillustrated in FIG- URE 5 the flexible coupling assembly comprises ashaft 23 shaped and adapted to be removably attached to a driving membersuch as the handpiece 22 as shown in FIG- URE 3 of conventional dentaldrilling equipment. The shaft 23 has an enlarged portion shown generallyat 24 and means extending from the enlarged portion and being radiallydisposed relative to the major axis of the shaft 23. A cooperatingmember 26 is configured to receive the extending means 25 and 26 so asto be drivable about an axis of rotation which may be angularly disposedin slight deviation with respect to the axis of rotation of the shaft23. Additionally, the assembly of FIGURE 5, and more particularly thecooperating member 27, includes means to receive and hold a drill 20.The particular configuration of the elements of the flexible couplingassembly of FIGURE 5 may perhaps be seen more clearly in the explodedperspective view of FIGURE 5a wherein like members bear the samenumerical designation. As seen in FIGURE 5a the shaft 23 has an enlargedend portion comprising a rounded end 24 of generally spherical shape andhaving a larger diameter than the shaft 23. Opposed pin members 25 and26 extend radially from the rounded end portion 24 with respect to themajor axis of the shaft 23. A cup-like member 27 is configured anddimensioned to receive the spherically shaped end portion 24 Within itsWalls. Slots 29 and 30 in the walls of the cup-like member 27 receiveand engage the opposed extending pins 25 and 26. Thus the rotationaltorque of the shaft 23 is transmitted through the pins 25 and 26 to thecup-like member 27 and thence to the drill which is held and received inappropriate means 28 within the cup-like member 27.

As may be appreciated from the exploded perspective view of FIGURE 5a,the enlarged end portion 24 of the shaft 23, when seated in the cup-likemember 27, allows and accommodates some angular misalignment of theshaft 23 with respect to the drill 20- without disturbing or changingthe axis of rotation of the drill 20, the driving torque beingtransmitted through the radially extending pins and 26. Thus the drill20 may be guided in a desired drilling position in accordance with aparticular alignment and drill a hole along the axis of such alignmentthough the shaft 23 deviates in its angular displacement with respect tothe guided alignment of drill 20.

In accordance with the concept of the present invention, thedetermination of the alignment of parallelism of the guiding means fordrilling parallel holes is accomplished in a dental laboratory undercontrolled conditions and with appropriate instrumentation. Limitedaccess and angular difiiculties such as might be encountered inperforming that work directly on the patient are largely eliminated.

Moreover, in accordance with the concept of the present invention, thoseskilled in the art will appreciate that diiferent lengths of bushingsmay be selected for use with a drill of known length therebypredetermining the depth to Which parallel holes will be drilled asdesired. Accordingly, when a drill of a known length is to be used, ashorter tubular bushing will provide a deeper parallel hole, while alonger tubular bushing will provide a shallower parallel hole with thesame length drill. Similarly if tubular bushings of a uniform length areemployed, the parallel holes drilled with a drill of known length willall be of the same controlled depth.

While I have disclosed only certain procedures and embodiments of themethod and apparatus of the invention, it will be readily appreciatedthat many modifications thereof may be made. I therefore intend by theap- 6 pended claims to cover all such modifications as fall with in thetrue spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A method and procedure of restorative dentistry comprising the stepsof preparing a patients teeth including making small indentations on atleast one of said teeth to establish the desired locations for parallelpin holes for receiving and retaining a restorative device; making anegative impression of the patients teeth including said indentations;forming a model of the patients teeth from said negative impressionincluding said indentations; positioning on said model a tubular bushingover each of said indentations, said bushings being arranged in parallelrelation to each other and aflixed to a common base forming a removablenegative impression of said model; drilling parallel pin holes in saidmodel through said bushings using a drill driven by a flexible coupling;forming a fitted restorative device from said model including parallelpins spaced and aligned in accordance with said parallel pin holesdrilled in said model; fitting said removable negative impressionincluding said bushings over the patients teeth; drilling parallel pinholes in the patients teeth through said bushings using a drill drivenby a flexible coupling; and afiixing said restorative de vice to thepatients teeth by inserting said parallel pins into said parallel pinholes.

2. A method and procedure of restorative dentistry comprising the stepsof preparing a patients teeth including making small indentations on atleast one of said teeth to establish the desired locations for parallelpin holes of predetermined depths for receiving and retaining arestorative device; making a negative impression of the patients teethincluding said indentations; forming a model of the patients teeth fromsaid negative impression including said indentations; positioning onsaid model a tubular bushing over each of said indentations, saidbushings being of a length to permit drilling only to said predetermineddepths with a drill of known length and being arranged in parallelrelation to each other affixed to a common base forming a removablenegative impression of said model; drilling parallel pin holes in saidmodel with a drill of said known length driven by a flexible coupling;forming a restorative device from said model including parallel pinsspaced and aligned in accordance with said parallel pin holes drilled insaid model; fitting said removable negative impression including saidbushings over the patients teeth; drilling parallel pin holes of saidpredetermined depths in the patients teeth through said bushings using adrill of said known length driven by a flexible coupling; and affixingsaid restorative device to said patients teeth by inserting saidparallel pins into said parallel pin holes.

3. A method and procedure of restorative dentistry comprising the stepsof preparing a patients teeth including making small indentations on atleast one of said teeth to establish the desired locations for parallelpin holes of a plurality of predetermined depths for receiving andretaining a restorative device; making a negative impression of thepatients teeth including said indentations; forming a model of thepatients teeth from said negative impression including saidindentations; positioning on said model a tubular bushing over each ofsaid indentations, each of said bushings being of a length inverselyproportional to the predetermined depth of hole desired at its positionto permit drilling only to said plurality of predetermined depths with adrill of known length and being arranged in parallel relation to eachother aflixed to a common base forming a removable negative impressionof said model; drilling parallel pin holes of said plurality ofpredetermined depths in said model with a drill of said known lengthdriven by a flexible coupling; forming a restorative device from saidmodel including parallel pins aligned and dimensioned in accordance withsaid parallel pin holes drilled in said model; fitting said removablenegative impression including said bushings over said patients teeth;drilling parallel pin holes of said plurality of predetermined depths inthe patients teeth through said bushings using a drill of said knownlength driven by a flexible coupling; and afiixing said restorativedevice to said patients teeth by inserting said parallel pins into saidparallel pin holes.

4. A method and procedure of restorative dentistry comprising the stepsof preparing a patients teeth including establishing the desiredlocation for parallel pin holes for an intended restorative device on atleast one of said teeth for receiving and retaining a restorativedevice; making a negative impression of the patients teeth includingsaid established desired locations for parallel pin holes; forming amodel of the patients teeth from said negative impression including saiddesired locations for parallel pin holes; positioning on said model atubular bushing over each of said established desired locations ofparallel pin holes, said bushings being arranged in parallelrelationship to each other and affixed to a common base forming aremovable negative impression of said model; drilling parallel pin holesin said model through said bushings;

forming a fitted restorative device from said model including parallelpins spaced and aligned in accordance with said parallel pin holesdrilled in said model; fitting said removable negative impressionincluding said bushings over the patients teeth; drilling parallel pinholes in the patients teeth through said bushings using a drill drivenby a flexible coupling, and afiixing said restorative device to thepatients teeth by inserting said parallel pins into said parallel pinholes.

References Cited UNITED STATES PATENTS 2/1966 Harris 32-67 Louis 6.MANCENE, Primary Examiner.

ROBERT E. MORGAN, Examiner.

